Download Non-Cardiac Surgery for Adults with CHD

The Adult With Congentital Heart Disease
James A. DiNardo, M.D., FAAP
Senior Associate in Cardiac Anesthesia
Children’s Hospital Boston
Associate Professor of Anaesthesia
Harvard Medical School
A conservative estimate of the number of adult patients with congenital heart
disease in the United States was 787,800 in the year 2000; approximately 117,000 of
which have truly complex disease 1. Data from Quebec indicates that 49% of those alive
in 2000 with severe congenital heart disease were adults 2. Management of these patients
has been extensively addressed in a 5 part Task Force statement from the American
College of Cardiology 1 3 4 5 6. Similar consensus documents have recently been
generated by the Canadian Society of Cardiology 7 8 9 and the European Society of
Cardiology 10.
The issues which must be evaluated in all adult patients with congenital heart
disease can be rightfully be characterized as residua (lesions for the most part
intentionally left behind at the time of reparative surgery) or sequalae (necessary
consequences of reparative operations or the natural history of the lesions) 11. These will
be discussed in detail.
Arrhythmias are common in these patients and have been recently reviewed
extensively 12.
Several lesions deserve particular attention as they are commonly encountered
and are subject to a number of misconceptions:
Tetralogy of Fallot (TOF)
It is becoming increasing clear that the presence of pulmonary insufficiency
resulting from trans-annular patch repair of TOF results in more long-term morbidity and
mortality than previously appreciated 13 14 15. The pathophysiology is strikingly similar to
that seen in chronic AI. Pulmonary valve replacement (surgical or percutanous) may be
necessary in certain subsets of these patients.
Arterial Switch Procedure (ASO) for D-TGA
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This is a subset of patients with congenital heart disease is generally considered to
be “cured”. Recent evidence demonstrates that these patients may have stress-induced
perfusion defects and attenuated coronary blood flow reserve 16 perhaps related to
sympathetic denervation 17.
Fontan Physiology
The essential function of the RV is not only to provide pulsatile flow through the
pulmonary arterial system but to maintain a low pressure in the highly compliant
systemic venous system, particularly the splanchnic bed 18. A single ventricle is capable
of pumping through both the systemic and pulmonary circulations arranged in series.
However, the lack of an RV reservoir requires that systemic venous pressure be elevated,
as there is, in essence, a continuous column of blood from the aorta to the systemic
capillaries, systemic veins, pulmonary capillaries, and finally the pulmonary veins.
Normally 70% of the total blood volume is contained on the venous side of the
circulation with the venous circulation having a capacitance 19 times that of the arterial
circulation. Fontan patients adapt to reduce venous capacitance (reduce unstressed
volume) so that elevated systemic venous pressure can be maintained with a normal
systemic venous volume (increased stressed volume). This makes them particularly
vulnerable to stimuli that reduce stressed volume such as increased venous capacitance
(loss of muscle tone, venodilation from any source) and reductions in vascular volume
(blood loss or dehydration). Figure 1.
Pulmonary blood flow in the Fontan circulation is NOT “passive”. This common
misconception inhibits the ability to fully understand Fontan physiology. Pulmonary
blood flow in Fontan circulation is non-pulsatile, continuous flow; the systemic ventricle
provides the driving energy for this flow. The Fontan circulation places the systemic and
pulmonary vascular resistances in series with the systemic ventricle. Figures 2 and 3.
Unfortunately, non-pulsatile pulmonary blood flow increases PVR by approximately
100% over than seen with pulsatile flow. Approximately 1/3 of the pulsatile energy
generated by the RV is absorbed by the proximal pulmonary arterial system and
redistributed in diastole to maintain recruitment of distal pulmonary vasculature. Loss of
recruitment of distal pulmonary vasculature effectively reduces the area of the pulmonary
vascular bed. This PVR increase is further exacerbated by the reduction in endothelial
release of NO which accompanies long-term loss of pulsatile pulmonary blood flow 19. In
addition, in the absence of pulsatility the total hydraulic power (mean + pulsatile flow) is
converted into a pure pressure gradient, increasing the energy necessary for transmission
of blood through the pulmonary circulation 20. The end result is an increase in the
afterload on the single ventricle and an reduction in ventricular efficiency 21 22 23. This
makes Fontan patients vulnerable to further increases in afterload (PVR or SVR) and to
reductions in contractility.
Positive pressure ventilation in Fontan patients is generally considered to be
detrimental. The presumptive mechanism is the mechanical impediment of pulmonary
blood flow with reduced delivery of blood to the systemic ventricle (reduced preload).
Mechanical ventilation with reduced tidal volumes and low mean airway pressure may
not be as detrimental to cardiac output in these patients as the factors generally associated
with intubation and ventilation, specifically anesthesia/sedation (reduction of sympathetic
output) and muscle relaxation (loss of muscular tone contribution to venous tone).
Management of Fontan patients is further complicated by global impairment of cardiac
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autonomic nervous activity with reduced heart rate variability and baroreceptor
sensitivity 24.
REFERENCES
1.
Warnes CA, Liberthson R, Danielson GK, et al.: Task force 1: the
changing profile of congenital heart disease in adult life. J Am Coll Cardiol 2001; 37:
1170-5
2.
Marelli AJ, Mackie AS, Ionescu-Ittu R, et al.: Congenital heart disease in
the general population: changing prevalence and age distribution. Circulation 2007; 115:
163-72
3.
Foster E, Graham TP, Jr., Driscoll DJ, et al.: Task force 2: special health
care needs of adults with congenital heart disease. J Am Coll Cardiol 2001; 37: 1176-83
4.
Child JS, Collins-Nakai RL, Alpert JS, et al.: Task force 3: workforce
description and educational requirements for the care of adults with congenital heart
disease. J Am Coll Cardiol 2001; 37: 1183-7
5.
Landzberg MJ, Murphy DJ, Jr., Davidson WR, Jr., et al.: Task force 4:
organization of delivery systems for adults with congenital heart disease. J Am Coll
Cardiol 2001; 37: 1187-93
6.
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congenital heart disease: access to care. J Am Coll Cardiol 2001; 37: 1193-8
7.
Therrien J, Dore A, Gersony W, et al.: CCS Consensus Conference 2001
update: recommendations for the management of adults with congenital heart disease.
Part I. Can J Cardiol 2001; 17: 940-59
8.
Therrien J, Gatzoulis M, Graham T, et al.: Canadian Cardiovascular
Society Consensus Conference 2001 update: Recommendations for the Management of
Adults with Congenital Heart Disease--Part II. Can J Cardiol 2001; 17: 1029-50
9.
Therrien J, Warnes C, Daliento L, et al.: Canadian Cardiovascular Society
Consensus Conference 2001 update: recommendations for the management of adults with
congenital heart disease part III. Can J Cardiol 2001; 17: 1135-58
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Deanfield J, Thaulow E, Warnes C, et al.: Management of grown up
congenital heart disease. Eur Heart J 2003; 24: 1035-84
11.
Perloff JK, Warnes CA: Challenges posed by adults with repaired
congenital heart disease. Circulation 2001; 103: 2637-43
12.
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disease. Circulation 2007; 115: 534-45
13.
Geva T, Sandweiss BM, Gauvreau K, et al.: Factors associated with
impaired clinical status in long-term survivors of tetralogy of Fallot repair evaluated by
magnetic resonance imaging. J Am Coll Cardiol 2004; 43: 1068-74
14.
Knauth AL, Gauvreau K, Powell AJ, et al.: Ventricular Size and Function
Assessed by Cardiac MRI Predict Major Adverse Clinical Outcomes Late After
Tetralogy of Fallot Repair. Heart 2006
15.
Geva T: Indications and timing of pulmonary valve replacement after
tetralogy of Fallot repair. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2006:
11-22
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16.
Hauser M, Bengel FM, Hager A, et al.: Impaired myocardial blood flow
and coronary flow reserve of the anatomical right systemic ventricle in patients with
congenitally corrected transposition of the great arteries. Heart 2003; 89: 1231-5
17.
Kondo C, Nakazawa M, Momma K, et al.: Sympathetic denervation and
reinnervation after arterial switch operation for complete transposition. Circulation 1998;
97: 2414-9
18.
Furey SA, 3rd, Zieske HA, Levy MN: The essential function of the right
ventricle. Am Heart J 1984; 107: 404-10
19.
Khambadkone S, Li J, de Leval MR, et al.: Basal pulmonary vascular
resistance and nitric oxide responsiveness late after Fontan-type operation. Circulation
2003; 107: 3204-8
20.
Mace L, Dervanian P, Bourriez A, et al.: Changes in venous return
parameters associated with univentricular Fontan circulations. Am J Physiol Heart Circ
Physiol 2000; 279: H2335-43
21.
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and single-ventricle circulation with blalock-taussig shunts. Circulation 2002; 105: 288592
22.
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bidirectional glenn procedure and total cavopulmonary connection. Ann Thorac Surg
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Figure 1. Elastic systemic illustrating the concepts of unstressed and stressed veins.
Theunstressed volume is the volume necessary to fill the vessel to the point just below
where intraluminal pressure is created. Unstressed volume does not generate a driving
pressure in the circulation. Additional volume will create an intraluminal pressure; this is
stressed volume. Unstressed volume can be reduced by reducing the size of the vessel
(vasoconstriction) or increased by increasing the size of the vessel (vasodilatation).
Stressed volume is the driving pressure in the circulation. Larger increases in pressure
can be obtained for a given stressed volume by reducing vessel compliance.
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Figure 2. Hydraulic circulation model. Normal series circulation is modeled with both
pumps functioning and clamp B applied. Fontan physiology is modeled with the RV
pump off and clamp B open. There is nothing “passive” about pulmonary blood flow.
RS= systemic vascular resistance, RP= pulmonary vascular resistance, CAP= pulmonary
arterial capacitance, CVP= pulmonary venous capacitance, CVS= systemic venous
capacitance, CAS= systemic arterial capacitance
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Figure 3. Acute transition from normal circulation to Fontan circulation using the model
in Figure 2. At the arrow the RV pump is shunt down and the clamp B is removed (RV
failure). Increased LV contractility and volume infusion are seen to correct the decreases
in cardiac output and systemic blood pressure (PAS). PVS= systemic venous pressure, PVP=
pulmonary venous pressure
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